Radially Coacting Ring Seal for Turbine Thermal Displacement
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Solution Overview
Problem
Turbine engine seals face challenges in sealing between cylindrical components with large radial and axial displacements due to cyclic temperature variations and high pressure differentials, particularly in asymmetrically oriented surfaces, where existing solutions require thick sections that are prone to high stresses and costly to manufacture.
Innovation Solution
A radially coacting ring seal apparatus with obliquely angled mating faces that function as a wedge to enhance radial sealing, allowing for axial and radial interaction, and featuring rounded corners for enhanced sealing contacts, reducing the need for thick hoop sections and accommodating thermal expansions and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick full-hoop section is used to provide robust rails and axial seal face, then sealing reliability under high axial loads is improved, but stress under thermal gradients increases and manufacturing cost increases
Solution Approach 1:
The seal is segmented into two separate ring portions (first and second ring portions) that coact radially rather than using a single thick full-hoop section. This segmentation allows each ring to be thinner while maintaining sealing reliability through their cooperative radial sealing action, thereby reducing stress under thermal gradients.
Solution Approach 2:
The sealing mechanism transitions from relying on axial seal faces to utilizing radial coaction between the two ring portions. By adding the radial sealing dimension, the design achieves reliable sealing without requiring the excessive axial thickness that would create high thermal stress.
2Reliability
If a piston ring with thick section is used to accommodate large axial deflections, then sealing capability under high pressure differentials is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The sealing function is divided between two separate ring portions that coact radially. This segmentation provides the necessary sealing capability under high pressure differentials while keeping each individual ring simpler and thinner than a single robust piston ring would require.
Solution Approach 2:
The two ring portions have different orientations (one radially oriented, one axially oriented) that work together to provide sealing. This asymmetric arrangement allows accommodation of large axial deflections and high pressure differentials without requiring a complex thick-section design.
3Reliability
If rounded corners are added to create enhanced sealing surfaces, then sealing contact is improved, but manufacturing complexity increases
Solution Approach 1:
Rounded corners are applied locally at specific sealing contact points rather than throughout the entire component. This localized application enhances sealing contact where needed while keeping the overall manufacturing process relatively simple and cost-effective.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides effective sealing over a wider range of thermal displacements with at least three sealing contacts, reducing stress and manufacturing costs while maintaining reliability in high-temperature, high-pressure environments.
Implementation Method 1
The obliquely angled mating faces may form a separate sealing interface between the outer or upper sealing ring portion and inner or lower sealing ring portion, in addition to the seal of the circumferential gap provided by the ring seal apparatus. The sealing interface between the outer or upper sealing ring portion and inner or lower sealing ring portion functions as a wedge to enhance radial sealing of the ring seal apparatus.
Implementation Method 2
Turbine engine seals are subject to relatively high and cyclic temperature conditions, ranging from atmospheric to 871°C (1600°F). The cyclic temperature variation results in expansions and contractions of parts, including radial and axial displacements of seals within their seats.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A ring seal apparatus for high temperature sealing includes a first ring including a pair of radial faces and a second ring including a second pair of radial faces, the second ring adapted to coact with the first ring. The first and second rings together define a pair of coacting mating faces. The mating faces are obliquely angled relative to the radial faces, such that each of the coacting mating faces is adapted to seal an interface of the two rings at an angle relative to their substantially parallel radial faces. The pair of coacting rings is adapted to seal a circumferential gap between a pair of components.